Heat Transfer in a Supercritical Fluid: Classification of Heat Transfer Regimes
Heat Transfer in a Supercritical Fluid: Classification of Heat Transfer Regimes
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DOI：
10.13182/nt06-a3738
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发表时间：
2006-06
影响因子：
1.5
通讯作者：
K. Seo;M. Kim;M. Anderson;M. Corradini
中科院分区：
文献类型：
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作者：
K. Seo;M. Kim;M. Anderson;M. Corradini
由于超临界流体的物理性质随温度的变化而发生剧烈的变化，现有的工程关联式或模型都不能准确地预测超临界流体的传热。本文旨在对现有模型适用的条件进行分类，并更好地理解这些局部传热机制。第一个目标是本文的重点。利用FLUENT软件计算了不同热流密度和质量流量条件下的壁面温度，并与实验数据进行了比较。由于该模型是为各种水流条件开发的，因此有必要作出某些假设。模拟结果表明，与高质量通量条件下，浮力效应可以忽略不计的协议。然而，FLUENT模型难以预测在高热流和低质量通量的组合条件下看到的局部低传热速率。一个新的广义参数，依赖于热量和质量通量，开发分类在何种条件下，这个FLUENT标准模型是适用的。该整体弗劳德数可用作参数来预测在哪些条件下浮力效应将占主导地位，并且将发生较低的传热速率。
Because of the dramatic variation of physical properties with a modest change of temperature, no existing engineering correlation or models can accurately predict heat transfer of supercritical fluids. This paper seeks to classify the conditions where the existing models are applicable and to better understand these local heat transfer mechanisms. The first objective is the focus of this paper. FLUENT was employed to compute the wall temperatures for various heat flux and mass flux conditions and to be compared with experimental data. Because the model was developed for a wide range of flow conditions, it was necessary to make certain assumptions. The simulations showed a good agreement with high mass flux conditions, where buoyancy effects could be neglected. The FLUENT model, however, had difficulty predicting the localized low heat transfer rates seen in the combined condition of high heat flux and low mass flux. A new generalized parameter, dependent on the heat and mass flux, was developed to classify under which conditions this FLUENT standard model was applicable. This global Froude number can be used as the parameter to predict under which conditions the buoyancy effect will be dominant and lower heat transfer rates will occur.